Although this is my first post, I've read thousands of posts here before I decided to add something.
For those who do or don't listen to lots of extreme metal, you might not know what to look for, so maybe this will help, in case you want to have your ears properly assaulted with such music as the musicians intended.
The "blast beats" actually date to jazz, but extreme metal made them a central pounding, torturing feature, repeated till you can't take it and stop the music or learn to appreciate it. If you don't have good extension into the sub-bass, the bass drum sounds like a second snare, and that sucks. Also, it needs to be clean sub-bass, so that in the space between each beat (and that could be at 240 BPM) you need to hear that space for the next beat to actually sound like a new assault upon your ears, and each beat should not alter the super-saturated nature of the extreme metal sound spectrum in the other frequencies.
Then the midrange needs to be strong. A sharp V sucks out the guitars and vocals or growls. This is bad...or awful. Midrange and sub-bass should be equally strong without mid-bass taking over.
As a poor, not-quite audiophile connoisseur, the Monoprice 8323 headphones (not the 8320 earphones) present an excellent cheap standard over-the-ear reference I use to judge IEMs. Here is my experience.
#0. Philips Fidelio S1: Not a budget IEM, so not fair to list except for comparison because I own it and it is great. But really, the next four on the list are just about equally good for much less cost.
#1.Jlab J6: With the right tips, this is better than any below. Also requires a lot of burn-in. Similar to the Fidelio S1, but with more midrange. Very durable, Very comfortable, low cord noise, best IEM with mic I've used. Many tips alter sound significantly, and you can alter the bass balance to your preference with tips. There can be a bit of sibilance until an extended break-in is done, but it will be gone. Don't underestimate these because Jlab has done lots of cheap consumer IEMs. These are awesome all-around.
#2. Id America Spark: It has most of the speed and detail of the JVC HA-FX40, but less of a mid cut, so excellent for metal. It is a bit uncomfortable to get them into a comfortable position in the ears, but I could do it, and then I was surprised that they fit there very comfortably for me while jogging.
#3. Vsonic GR99. Near the best I've owned/tried. I don't feel like there is much improvement beyond this in sound other than the microdetails, but it doesn't have a mic or play/pause button, and the cable is a bit thin.
#4. Philips SHE3575-3595: Insanely good when you can find for $10, just a little too much V shaped cut of midrange. Must buy separate silicone hybrids tips, or use some from another pair of IEMs. Cheap enough that you MUST TRY a pair or three for metal. Moderately comfortable for jogging. I've found no sound difference between my 3575 and 3590, but I can visually see that my 3575 isn't glued together as well. It doesn't affect sound quality on mine, but I guess I can understand those who have found a difference.
#5. Jlab J5: Similar to the J6. Excellent but more subbass, midbass, but chord noise that makes it is a bit too microphonic for for jogging. Well built. There are times I want to relax with alcohol, a super comfortable IEM with a nice bass boost without scooping mids, and this is usually what I choose.
#6. Brainwavz Beta: Midrange centric, but extends into subbass with breakin, but maybe the least treble extension of any IEM I've owned, not as reviews describe. MP4Nation replaced an original dud, but so far, this has been my most comfortable and consistent jogging IEM. I can go an hour without adjusting it.
#7.JVC FX40: Massive midcut hurts what would otherwise be unparalleled detail. On some songs, this is the best I own, on others it is hollow and unnatural because guitars and vocals are recessed. Requires way too many hours break-in, and the only IEM I prefer Complys with, but I still love to use these on occasion.
#8. Philips SHE9550: Almost the same as SHE3575-3595, but comes with useable tips. Comfortable except for jogging, where they form a pressure seal that can be painful.
#9. Sony XB21EX: A bit too much bass, but at least not bloated, Not bad for jogging.
#10. Monoprice 8320: Just a bit deficient in sub-bass. Otherwise awesome, but own a pair anyway at the price. My wife washed a pair and after air drying, they sound unharmed. I no longer let my wife wash my clothes. She might have done it on purpose.
#11. MeElectronics M6: Too much V shape mid cut, but otherwise good. I wish I had got the microphone version. I'd use it for jogging more if it did.
#12. Brainwavz Alpha. Very good tonal balance and full sub-bass with the right tips. Just a little missing in detail and impact release relative to most of the others.
#13. MeElectronics M9: Too much V shape mid cut
#14. Philips SHE7005a: Thought it would be a variation on the SHE3580, but it's not...or maybe it is. It is a quality fast, clear response, but without most of the bass of the SHE3580. You can still hear good impact with bass drums, nevertheless.
#15. Jlab J4: Way too much mid-bass, but the most bullet proof IEM I own. Good for loaning to my kids who would otherwise destroy IEMs.
#16. Philips SHE5105: Very low build quality. I can't use it with a smartphone because the bad button connection randomly pauses or increases volume. Not comfortable for any body movement. I can still use it sitting down with a PC and sound is great though. More bass and midrange than the SHE3580. Louder in general, more of everything except treble.
#17. Sony EX-71: Had these for a decade. Missing deep sub-bass, but I love that they've lasted so long.
#18. Philips earbuds SHE2650: Not good for metal
#19. Philips earbuds SHE 2641 Really not good for metal.
To sum up my budget recommendations for extreme metal, start with the SHE3575, Monoprice 8320, and Jlab J6M, as they represent the best deals, and you can decide what you prefer from there.
Edited by carltonh - 10/1/13 at 7:40pm